How Sword Swallowing Works

On the left, the relatively curvy human GI tract. On the right, a sword of comparable length.

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The human gastrointestinal (GI) tract is made of two types of muscle tissue - skeletal muscle and smooth muscle - and a lubricating layer known as the mucosa. In general, the movement of skeletal muscle is voluntary - you have conscious control over it. When you talk, type, blink and move, you're using skeletal muscle. The movement of smooth muscle, on the other hand, is generally involuntary. Smooth muscle is responsible for actions like the dilation of blood vessels and movement of food during digestion. Many of your body's activities, including breathing and eating, require the participation of both skeletal and smooth muscle tissue.

The portions of the GI tract made of skeletal muscle include your mouth, your pharynx and the upper portion of your esophagus, which connects your throat to your stomach. These are the parts of your GI tract that you have conscious control over. When you swallow, you consciously use your tongue to move the food toward your pharynx. Your larynx then moves upward, and a ring of muscle called the upper esophageal sphincter relaxes. This allows the food, or bolus, to move into your esophagus. A flap of tissue known as the epiglottis seals off your windpipe during this process so the food doesn't go into your lungs.

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The actions of the rest of your GI tract are involuntary. When the bolus reaches the part of your esophagus lined with smooth muscle, an automatic process called peristalsis takes over. The ring of muscle tissue just above the bolus squeezes together, forcing the bolus down toward the stomach. Then, the process repeats itself until the food reaches the stomach. A second sphincter, the lower esophageal sphincter, relaxes to allow the bolus into the stomach.

This whole process takes place in very close proximity to other organs in your body, including your: